1. Field
The present invention relates generally to image compression and, more specifically, the computer-implemented techniques to improve image or video quality or encoding performance by enhancing discrete cosine transform coefficients.
2. Description of the Related Art
Data compression underlies much of modern information technology infrastructure. Compression is often used before storing data, to reduce the amount of media consumed and lower storage costs. Compression is also often used before transmitting the data over some media to reduce the bandwidth consumed. Certain types of data are particularly amenable to compression, including images (e.g., still images or video) and audio.
Prior to compression, data is often obtained through sensors, data entry, or the like, in a format that is relatively voluminous. Often the data contains redundancies that can be leveraged to reduce the amount of data needed to represent the original data. Further, in some cases, end users are not particularly sensitive to portions of the data, and these portions can be discarded to reduce the amount of data used to represent the original data. Compression can, thus, be lossless or, when data is discarded, “lossy,” in the sense that some of the information is lost in the compression process.
A common technique for lossy data compression is the Discrete Cosine Transform (DCT). Data is generally represented as the sum of cosine functions at various frequencies, with the amplitude of the function at the respective frequencies being modulated to produce a result that approximates the original data. At higher compression rates, however, a blocky artifact appears that is undesirable. Complicating this issue, in many use cases, it is difficult to select other compression techniques because of considerable existing investment premised on the use of DCT.